OH and no it's not pulling these from bookmarks, bookmarks are displayed in the address bar with a little blue star at the front, these are a single suggestion at the very top of the dropdown list, and these ones don't have any icon at all, as if they are being pulled from the history....which is empty.

The autofill feature -- meaning the top level domains Firefox shows in the address bar itself -- are stored in a separate table from the list of visits you have made to a site. Even if all the visits are deleted, the top level domains may linger in the database.

I think Firefox should clean them up eventually but if it doesn't, there's another option: "Forget About This Site." In order to use this feature, you do need to have at least one visit to the site in history. Then you can:

(1) Open the Library window to history (Ctrl+Shift+h or "Show All History)

(2) Use the search box at the upper right to filter the list down to only the things you want to completely flush (this helps avoid accidents)

(3) Right-click an entry and choose "Forget About This Site" -- it's thoroughly destructive and should clean out all kinds of history

If there is a more convenient way, hopefully someone who knows will mention it.